Integrated circuit (IC) packages are commonly used to interconnect a semiconductor die mounted in or on the package to a printed circuit board (PCB). Among other functions, the package acts to protect the die from environmental elements and to provide an electrical interface with the PCB. The substrate typically includes two sets of connectors (one set for connection to the die, the other set for connection to the PCB) that are generally interconnected by a multi-layered circuit. There exists a variety of methods for interconnecting the die to the package substrate and for interconnecting the substrate to the PCB. For example, in flip-chip packages an array of solder bumps connects the die to the package substrate. Other methods, such as, wire bonding, are also used. Pin grid arrays (PGAs), ball grid arrays (BGAs), land grid arrays (LGAs), and other known methods are commonly used to connect the substrate to the PCB.
Die-up and die-down packages currently exists. In die-up packages the IC die is mounted onto a top surface of the substrate opposite the surface that interconnects with the PCB. In die-down packages the die is mounted on the bottom surface of the substrate which is the same side that interconnects with the PCB. In die-down packages the die resides below the topside surface of the PCB. Because very little real estate exists below the PCB, temperature management of the die by the removal of heat from its backside presents a challenge.